Footnotes

1 J. V. Taylor Tavares is funded by the National Institute of Mental Health Intramural Research Programme as part of the National Institutes of Health – University of Cambridge Health Science Scholars Programme. W. C. Drevets is funded by the National Institute of Mental Health Intramural Research Programme. B. J. Sahakian's research is funded by a Wellcome Trust Programme Grant (Number 019407).We would also like to thank Professor T. W. Robbins and J. P. Roiser for discussion.